Multiply, reduce to lowest terms, and write as a mixed number: $ 5\dfrac{1}{4} \times 2\dfrac{4}{5} $
$ = \dfrac{21}{4} \times \dfrac{14}{5}$ $ = \dfrac{21 \times 14}{4 \times 5}$ $ = \dfrac{294}{20}$ $ = \dfrac{147}{10}$ $ = 14 \dfrac{7}{10}$